In the medical imaging field, oftentimes the field of view of the imaging devices is smaller than the anatomy being examined. Consequently, two or more individual images need to be obtained and then properly assembled to form the appropriate field of view for analysis. Such assembly of the images is referred to hereinafter as “stitching.”
The need for stitching is encountered in many digital radiography, MRI, ultrasound, and nuclear medicine evaluations, all techniques that are capable of imaging along the axis of possible motion. Unfortunately, stitching of the images is not always straightforward. Because it is not always known how much the patient or the imaging device has moved or how much the patient shifts or rotates between image shots, accurate stitching of the individual images often proves difficult. Thus, flexibility of the stitching the images is desirable.
One particular use in which stitching is often used is in a scoliosis evaluation. Scoliosis is defined as a substantial lateral curvature of the vertebral column that usually has its onset during periods of rapid growth. Scoliosis curve is determined to be present when a structural vertebral column curve of 11° or more is measured in the coronal plane roentgenogram of the erect patient. Radiologic imaging of the spine has traditionally been used in the identification, classification, and monitoring of scoliosis. Early detection and bracing treatment of juvenile and adolescent idiopathic scoliosis has decreased the need for surgery.
In scoliosis evaluations it is often necessary to stitch the radiographic image of the thoracic and upper lumbar spine with the radiographic image of the lumbar and lower thoracic spine to provide a large enough field of view to allow the physician to measure the angle of scoliosis or the “Cobb angle.” Unfortunately, conventional “stitching” methods of drawing and measuring directly on the radiographic film have been found to be inaccurate, and sometimes introducing errors of ±5°–10°, or more.
Such large alignment errors can affect the perceived alignment of the anatomy and dramatically affect the choice of treatment of the patient. For example, when the angle of scoliosis is mild (0°–20°), the recommended treatment is observation and careful follow-up. For moderate scoliosis (20°–40°), bracing is recommended, while severe scoliosis (greater than 50°) surgical fusion of the spine is recommended. Thus, the physicians' evaluation and the choice of treatment is highly dependent on the evaluation of the stitched image. Unfortunately, because the conventional stitching methods can introduce deviations of ±10° or more, the measured angle of scoliosis from the stitched image would likely not accurately indicate to the physician how severe a case of scoliosis was present in the patient.
Accordingly, what are needed are methods, software, and systems that provide an accurate means for stitching images. It would also be desirable to provide a highly versatile set of choices that can increase the ease of stitching. It would further be desirable to provide improved quality of the stitched image, especially in the overlap section of the stitched images.